Types of Arthrogryposis

The recognized definition of Arthrogryposis Multiplex Congentia (AMC) is a condition that causes congenital contractures of two or more body parts. It is important to remember that AMC is not a diagnosis but is an umbrella term that covers over 300-400 different types of conditions and syndromes.

A simple way to categorize this complex issue is:

Amyoplasia

Amyoplasia (A = no, myo=muscle, plasia=growth) means no muscle growth and is the most common type of AMC . It is estimated that one third of people born with AMC will have Amyoplasia about 1 in 10,000 and it’s typically referred to as ‘Classical type AMC.’ This is considered the non-genetic form of AMC, meaning there has been no mutation in the genes to cause the condition to be present, and is not passed down from the parents.

Common traits of people with Amyoplasia are:

Affected in both arms and legs, and often the spine

Internally rotated shoulders

Extended elbows

Flexed wrists

Contractors of the fingers

Lower limbs can be stuck in various positions

Hips can have flexion/abduction/external rotational contractures (Buddha position or frog position)

Dislocated hips (about 30%)

Hip extension contractures (less common)

Flexion contractures of the knees

Extension contractures of the knees (less common)

Club feet

About 10% affected individuals may have squashed or missing fingers and toes. (less common)

Scoliosis (20-30%)

Splotchy red mark on the face (stork bite)

About 10% of Amyoplasia cases individuals may have abdominal abnormalities such as gastroschisis. Gastroschisis is a condition in which a hole is present in the wall of the abdomen allowing the intestines to intrude out of the abdominal space. (less common)

Distal

People with distal arthrogryposis (DA) are primarily affected in the hands and feet. Other areas and body functions can be affected depending on what type one has. There are currently 20+ different types of DA all of which are linked back to genetic mutations. The best way to learn about you or your child’s specific type is to discuss it with health care providers and people in the AMC community. Here are a few of the more common types of distal arthrogryposis.

Type 1:

Type 1 is characterized by joint deformities that restrict movement in the hands and feet.

Common traits of distal type 1 are:

Facial sparing

Multiple contractures in hands and feet

Clenched hands

Overlapping fingers

A hand deformity in which all of the fingers are angled outward toward the little finger. This is called ulnar deviation

Hips and knees can be affected but it is less common and usually mild

Club feet

Type 2A (Freeman-Sheldon Syndrome):

Freeman-Sheldon Syndrome primarily affects the hands, feet and face. Distinctive facial features such as a small mouth, with purse lips give the appearance of a whistling face, hence also being called “Whistling Face Syndrome”.

Common traits of Freeman-Sheldon Syndrome are:

Prominent forehead and brow ridges

Widely spaced eyes

Deep set eyes

Outside corner of the eyes that point downward

Narrowing of the eye openings

Droopy eye lids

Eyes that do not look in the same direction

Sunken appearance of the middle of the face

Short nose and a long area between the nose and the mouth

Deep folds in the skin between the nose and lips

Full cheeks

Small mouth with pursed lips

Chin dimple shaped like an H or a V

Small tongue and jaw and a high arch in the roof of the mouth

Difficulty swallowing

Multiple contractors in hands and feet

A hand deformity in which all of the fingers are angled outward toward the little finger. This is called ulnar deviation.

Club feet

Spine that curves to the side (scoliosis)

Failure to gain weight and grow at expected weight

Respiratory complications

Speech problems

Hearing loss

Malignant hyperthermia (MH) is a condition where people have negative reactions to certain drugs used during general anesthesia. If it is of concern you can speak to your doctor about avoiding the use of succinylcholine during general anesthesia.

Type 2B (Sheldon-Hall Syndrome):

Sheldon-Hall Syndrome is similar to Freeman Sheldon Syndrome in that both have joint contractures of various areas of the body. However there are enough differences between the two that they are considered separate conditions.

Common traits of Sheldon-Hall Syndrome are:

Triangular shaped face

Outside corner of the eyes that point downward

Deep folds in the skin between the nose and lips

Attached ear lobes

Small mouth with pursed lips

High arched roof of the mouth

Extra folds of skin on the neck

Permanently bent fingers and toes

Overlapping fingers

A hand deformity in which all of the fingers are angled outward toward the little finger. This is called ulnar deviation.

Club feet

Vertical talus deformity

Type 9 (Beals Syndrome):

Beals syndrome is also known as congenital contractural archnodactyly (CCA) and has many of the same features as Marfan Syndrome. While Beals and Marfan share similar features they are also very distinct in the way they affect a person so it is important to obtain a accurate diagnosis so appropriate treatment can be given.

Common traits of Beals syndrome are:

Abnormally shaped ears resulting in a crumpled appearance

Unusually small jaw and or high arched palate

Abnormal short neck

Rounded upper back

Chest sinks in or sticks out

Long narrow body type with long limbs

Abnormally long slender fingers and toes

Joints being stuck in a permanent flexed position

Contractors in elbows and hands

Contractures in feet

Club feet

Contractures affecting the hips, knees and ankles

Curved spine (scoliosis)

Backward or lateral curved spine

Reduced bone mass

Underdeveloped muscles

Cardiovascular complications. It is recommended that those with Beals Syndrome have their heart monitored yearly as a precaution because on occasion heart issues like aortic enlargement or mitral valve regurgitation can occur.

Everything Else

This category is one of the most complex due to the fact that there are over 250 different diagnosis. Anything that is not Distal or Amyoplasia AMC goes into everything else category.

These include,but not limited too:

Pterygium syndromes

Lethal conditions

Atypical AMC

Pterygium syndromes

Pterygium syndrome is a congenital condition where webbing of the skin occurs around the joints causing a lack of muscle movement which then causes muscle weakness and joint contractures. Escobar syndrome and Lethal multiple pterygium syndrome are a few pterygium syndromes that are connected to AMC. Escobar type multiple pterygium syndrome (Escobar syndrome). There are different types of pterygium syndromes, Escobar being one of the more common types.

Common traits of Escobar syndrome are:

Webbing of the skin that affects

Skin on the neck

Fingers

Forearms

Inner thighs

Backs of knees

Other Features

Droopy eye lids

Outside corners of the eyes point downward

Skin folds covering the inner corner of the eyes

Low set ears

Small jaw

Arms and legs that cannot fully extend

Scoliosis

Respiratory distress at birth due to underdeveloped lungs

Males can have undescended testes

Lethal multiple pterygium syndrome is tragically individuals with this form of multiple pterygium syndrome typically do not make it past the 2nd or 3rd trimester of pregnancy.

Common traits of Lethal multiple pterygium syndrome are:

Abnormally small head

An opening in the roof of the mouth which is called cleft palet

Fluid filled sac typically found on the back of the neck

Excessive fluid in the body

Severe multiple contractors

Underdevelopment of the heart, lungs, or brain

Twisting of the intestines

Kidney abnormalities

A hole in the muscle that separates the abdomen from the chest cavity

Lethal multiple pterygium syndrome also falls under the Lethal conditions subgroup in the Everything else category.

Lethal Conditions

Tragically it is estimated that 1/3 of babies born with AMC will either be still born or die during their first year of life. There are several forms of AMC that can be deadly. As mentioned above Lethal Multiple pterygium syndrome is one. Another is Cerebro-oculo-facio-skeletal (COFS) as well as Restrictive dermopathy. Cerebro-oculo-facio-skeletal syndrome (COFS) . People with COFS will progressively deteriorate and sadly many times will not survive past 7 years old.

Common traits of COFS can be:

Extremely small head

Abnormally small eyes

Clouding of the eyes lens (cataract)

Horizontally narrow opening between the eye lids

Unusually prominent nose

Abnormally large ears

Upper lip over lapping lower lip

Abnormally long groove in upper lip

Unusually small jaw

Elbows with flexion contractures

One line in the palm of the hand formed by the fusion of two lines

Hip deformities

Knees with flexion contractures

Congenital vertical talus deformity (rocker bottom)

Grove over the length of the soles of the feet

Osteoporosis

Lack of muscle tone

Feeding difficulties

Vulnerability to respiratory infections

Failure to thrive

Developmental retardation

Restrictive dermopathy – Restrictive dermopathy is a lethal genetic skin condition that is connected to AMC. Unfortunately most born with Restrictive dermopathy will not make it past the first week of life.

Common traits of Restrictive dermopathy are:

delayed and stunted prenatal growth

reduced fetal movements

excessive amount of amniotic fluid

premature rupture of the membranes

thin tight skin

translucent skin

skin with damage at body parts that bend

facial dysmorphism

joint ankylosis (stiffness or fixation of joints and/or union of separate bones to

form a single bone)

death with in the first week of life

Atypical AMC

Atypical AMC is a term used to describe individuals with a unknown type of AMC. AMC is rare and highly complex and it can take years for certain people to receive the diagnosis that caused AMC, and some may never receive a diagnosis at all. This can be a very long and frustrating journey for many families seeking answers about their loved ones with AMC, or a AMCer seeking answers for themselves.

AMCSI can connect you with support groups, other parents and caregivers through social media, mini-meet ups, and the yearly AMC conference. This will give you an enormous amount of moral support and also ideas for tools and adaptive equipment to help you or your child along.

AMC is a rare condition and it’s important to find an experienced doctor that will effectively treat you or your child. Whether you are Atypical or have a diagnosis you will need treatment and support groups are an excellent place to connect with others who can lead you in the right direction.